Unresolved problems in coronary care

Abstract

Recently the focus of the coronary care unit has shifted from resuscitation to prevention of cardiac arrest. From the data presented in this paper it appears that careful application of this policy will result in a one-third reduction in mortality among hospitalized patients with acute myocardial infarction. This result is achieved mainly by reducing the number of deaths due to unexpected catastrophic cardiac arrhythmias, e.g., primary electrical failure of the heart. Premonitory arrhythmias which herald the onset of such a catastrophe are defined as “arrhythmias of electrical instability” (multiple ventricular premature beats and ventricular tachycardia), and “arrhythmias of potential electrical instability” (bradycardia and heart block). Evidence is presented to show that aggressive treatment of these disorders should be employed. In this series of 300 hospitalized patients, death from myocardial infarction usually was due to overwhelming myocardial injury resulting in shock or pulmonary edema. Patients with this syndrome who do not respond immediately to catecholamines, digitalis and other routine measures carry an extremely poor prognosis; presently available methods have not significantly altered mortality in this group. Definitive treatment of intractable pump failure awaits the development of new technics such as circulatory assist devices. Immediate further reduction in mortality from acute myocardial infarction requires intelligent application of what has thus far been learned in the coronary care unit. Since sudden death prior to hospitalization, possibly due to arrhythmia, is still the chief cause of death from coronary occlusion, it follows that institution of coronary care unit technics closer in time to the onset of infarction may result in further salvage of life. The concept of “precoronary care” encompasses those measures required to effect this salvage. These include immediate hospitalization on mere suspicion of myocardial infarction, early electrocardiographic monitoring in emergency wards and in ambulances, and ultimately continuous telemetric monitoring of high-risk patients as they go about their daily tasks. Finally, it is clear that improved methods are needed for diagnosing myocardial infarction and for grading the severity of an attack. Standardized criteria should be established which will allow the vast accummulation of information currently pouring forth from coronary care units to be utilized in improving treatment of the disease.